Rosemary Butler, the Presiding Officer of the National Assembly, accepting Ieuan Wyn Jones' resignation. The former Plaid Cymru leader has stepped down with immediate effect to take up a role heading Menai Science Park. His resignation triggers a by-election for his Ynys Môn seat.
The battle for Ieuan Wyn Jone's Assembly seat has already begun. Anglesey's Labour MP has issued this statement:
The former Plaid Cymru leader Ieuan Wyn Jones has formally resigned as an AM. His resignation was accepted by the Assembly's Presiding Officer, Rosemary Butler.
Mrs Butler must now confirm the date of the Ynys Môn by-election, which is expected to be on August 1. Until then Labour will have a majority of one over all other parties in the Senedd.
The date of the Ynys Môn by-election will be set by the Assembly's Presiding Officer Rosemary Butler following Ieuan Wyn Jones' decision to resign his seat immediately.
The precedent is to respect the defending party's choice of date.
ITV Cymru Wales understands that Plaid will ask for August 1.
Ieuan Wyn Jones has announced he will stand down from the Assembly with immediate effect, triggering a by-election for the Ynys Môn seat.
The former Plaid Cymru leader said he 'felt an early by-election would be preferable' in order for a new Assembly Member to be elected before the start of the new term in September.
On Tuesday, Mr Wyn Jones announced his intention to stand down in order to take on the challenge of leading the new Menai Science Park.
Former Plaid Cymru leader Ieuan Wyn Jones is to leave politics and take up a new role. The Assembly Member today thanked the people of Ynys Mon - where he has been an AM since 1999.
A by-election will now take place when Mr Wyn Jones takes up his new role as Head of the Menai Science Park project.
Ian Lang reports.
"I'll actually be starting in the job in July, and then I'll be discussing with the party locally the precise that at which I'll be standing down from the Assembly" Ieuan Wyn Jones tells ITV News.
"That is something which we're currently in no rush to do because there's just been a local government election and people are exhausted after that."
Kirsty Williams, the leader of the Welsh Liberal Democrats, has paid tribute to Plaid Cymru's Ieuan Wyn Jones who's announced he's stepping down from the Assembly.
The departure of Ieuan Wyn Jones from the Assembly marks the end of a lengthy political career that often defied expectations. Despite a challenge which curtailed his leadership in 2003, he went on to regain overall control of Plaid Cymru and took the party into government with Labour in 2007.
Most agree that that first taste of government for Plaid and the achievement of a referendum which gave the Assembly lawmaking powers will form Ieuan Wyn Jones' legacy. He didn't have the charisma of leaders like Gwynfor Evans, Dafydd Elis-Thomas and Dafydd Wigley but he took his party into power.
A party strategist since he led Plaid Cymru's internal inquiry into the setbacks of 1979, Ieuan Wyn Jones emerged to snatch Ynys Mon at the 1987 General Election. Plaid lost the Westminster seat when he stood down from Parliament. Now it must defend the Assembly seat without him.
Opposition leader Andrew RT Davies has joined tributes to the former leader of Plaid Cymru, Ieuan Wyn Jones, who's announced he'll be stepping down from the Assembly.